Easy-题目53：257. Binary Tree Paths

题目原文：

Given a binary tree, return all root-to-leaf paths.

For example, given the following binary tree:

1
/   \
2     3
\
5

All root-to-leaf paths are:

[“1->2->5”, “1->3”]

题目大意：

给出一个二叉树，输出所有从根节点到叶子节点的路径。

题目分析：

遍历即可，注意每次向左右子树搜索的时候，把当前路径一直带在函数参数里面。

源码：（language：java）

public class Solution {
List<String> res = new ArrayList<String>();
public List<String> binaryTreePaths(TreeNode root) {
if(root != null) findPaths(root,String.valueOf(root.val));
return res;
}
private void findPaths(TreeNode n, String path){
if(n.left == null && n.right == null) res.add(path);
if(n.left != null) findPaths(n.left, path+"->"+n.left.val);
if(n.right != null) findPaths(n.right, path+"->"+n.right.val);
}
}

成绩：

3ms,beats 27.22%,众数3ms,47.28%.